Glued laminated timber, also called Glulam, is a type of structural timber product comprising a number
of layers of dimensioned timber bonded together with durable, moisture-resistant structural adhesives.
In North America the material providing the laminations is termed 'laminating stock' or lamstock for short.
By laminating a number of smaller pieces of timber, a single large, strong, structural member is manufactured
from smaller pieces. These structural members are used as vertical columns or horizontal beams, as well as curved,
arched shapes. Glulam is readily produced in curved shapes and it is available in a range of species and appearance
characteristics to meet varied end-use requirements.Connections are usually made with bolts or plain steel
dowels and steel plates.
Glulam optimizes the structural values of a renewable resource - wood. Because of their composition, large glulam
members can be manufactured from a variety of smaller trees harvested from second- and third-growth forests and
plantations. Glulam provides the strength and versatility of large wood members without relying on the old
growth-dependent solid-sawn timbers. It reduces the overall amount of wood used when compared to solid sawn timbers
by diminishing the negative impact of knots and other small defects in each component board.
Glulam has much lower embodied energy than reinforced concrete and steel, although of course it does entail more embodied
energy than solid timber. However, the laminating process allows timber to be used for much longer spans, heavier loads,
and complex shapes. Glulam is two-thirds the weight of steel and one sixth the weight of concrete the embodied energy
to produce it is six times less than the same suitable strength of steel.Glulam can be manufactured to a variety of
straight and curved configurations so it offers architects artistic freedom without sacrificing structural requirements.
Wood has a greater tensile strength relative to steel two times on a strength-to-weight basis and has a greater
compressive resistance strength than concrete.The high strength and stiffness of laminated timbers enable glulam beams
and arches to span large distances without intermediate columns, allowing more design flexibility than with traditional
timber construction. The size is limited only by transportation and handling constraints.